During a growing period of corn, etc., a triazine-based herbicide such as atrazine and acid anilide-based herbicides such as alachlor and metolachlor have been conventionally used. However, atrazine shows low efficacy to gramineous weeds, and alachlor and metolachlor show low efficacy to broad-leaved weeds. It is therefore difficult at present to control gramineous weeds and broad-leaved weeds together with a single herbicide. Further, the above herbicides are undesirable in view of an environmental problem due to their high dosage requirement.
On the other hand, it is known that specific 4-benzoyl-pyrazole derivatives have herbicidal activity (see JP-A-63-122672, JP-A-63-122673. JP-A-63-170365, JP-A-1-52759, JP-A-2-173 and JP-A-2-288866).
Further, for example, pyrazolate of the following formula is known as a commercial herbicide. ##STR2##
However, pyrazole derivatives having a thiochroman ring such as compounds of the present invention to be specified later are not known yet, and derivatives having an alkoxyimino group are not known, either.
Meanwhile, the commercially available pyrazolate is a herbicide for use in a paddy field., and it hardly has herbicidal activity when used in a plowed field. Further, in foliar treatment, the 4-benzoyl-pyrazole derivatives that have been already disclosed have activity to broad-leaved weeds such as cocklebur, velvetleaf, slender amaranth, etc., in a plowed field, while their activity is practically insufficient. Further, they show very poor activity to grasses such as green foxtail, fingergrass, barnyardgrass, etc. In soil treatment, the above derivatives show very poor activity to grasses such as green foxtail, crabgrass, barnyardgrass, etc, and to broad-leaved weeds such as cocklebur, velvetleaf, slender amaranth, etc.